Is there a software to reverse normal maps?
The process you are describing is called &quot;Baking&quot;. You can follow this process to do this, baking from selected to the active mesh: https://www.youtube.com/watch?v=MnipHJAQJbQ
Marmoset is a dedicated baking tool and has a lot of features and optimizations that make it especially efficient. You can also do this in substance painter. Other 3d softwares also support baking, but are not their specialty